Desecration, defecation and substance abuse are among the issues St Paul's Cathedral has had to cope with because of the protest camp in its churchyard, according to legal documents filed by the City of London Corporation ahead of its attempt to evict activists from the area.

Occupy London, which arrived outside the church on 15 October when it was denied access to nearby Paternoster Square, the home of the London Stock Exchange, faces multiple accusations of obstruction and disruption, from witnesses including Nicholas Cottam, the registrar of St Paul's.

The cathedral is not taking legal action to remove the encampment from its doorstep, but has always acknowledged the corporation's right to do so. Last week the corporation served notice on Occupy London, which has promised to fight any eviction attempts. The corporation claims the encampment obstructs the public highways around the cathedral, and is seeking to remove tents and other structures from the area. The two sides are expected in court this week.

In a letter to a corporation official, Cottam wrote: "Desecration: graffiti have been scratched and painted on to the great west doors of the cathedral, the chapter house door and most notably a sacrilegious message painted on to the restored pillars of the west portico.

"Human defecation has occurred in the west portico entrance and inside the cathedral on several occasions. Noisy interruption has occurred to spoken and sung Christian services, after repeated requests for quiet. Foul language has frequently been directed at cathedral staff. Noise has frequently carried into the cathedral to the extent that services have been difficult to sustain in any meaningful way."

Cottam added that alcohol "and other stimulants" appeared to "fuel the noise levels day and night".

In his witness statement, Cottam revealed that more than half of its school parties had cancelled since 15 October.

"We would normally expect thousands to visit at this time of year. The reason for their cancellations is directly as a result of their own risk assessments which take the view that entry and exit to the cathedral is in their opinion too difficult due to the camp's presence and heavy media interest. We have failed to overcome this fear."

He also said that had been a drop in visitor numbers and that these "should be twice what they now are".

There are also concerns that Occupy London is attracting vulnerable people.

Joy Hollister, a social worker, told the corporation that at the camp there were growing numbers of people who were "exhibiting behaviour indicative of poor mental health, people who were exhibiting signs of drug use, people who had body odour from significant periods without washing or change of clothing and a number of people who were clearly under the influence of drugs and alcohol".

She also noted that children were staying or spending time in the camp.

Occupy London did not address the issues raised in the 88-page legal bundle. It said it would issue a statement once it had reviewed the papers.

Another witness statement, from temporary police inspector John Zuber, said there was a "mounting concern of drugs within the camp" including cannabis and "what is currently believed to be a liquid class A drug". The camp had made requests for an official 'sharps' container for needles to be put into," he added.

The camp was not a safe place, especially after dark, said Zuber, and staff from local businesses felt intimidated walking through it. The St Paul's Cathedral choir school avoided the churchyard if they had to take children past the cathedral. This feeling of insecurity extended to protesters and Zuber cited evidence of a women-only area.